August 2017 Chemistry Regents #78-81

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Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Questions 51-52 Questions 53-54 Questions 55-58 Questions 59-60 Questions 61-65 Questions 66-68 Questions 69-72 Questions 73-77  Questions 78-81  Questions 82-85

 

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Questions 78-81

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Base your answers to questions 78 through 81 on the information below and on your knowledge of chemistry.

 The electrolysis of brine, a concentrated aqueous sodium chloride solution, produces three important industrial chemicals: chlorine gas, hydrogen gas, and sodium hydroxide. The diagram and equation below represent a brine electrolysis cell. Before the battery is connected, the pH value of the brine solution is 7.0

2NaCl(aq) + 2H2O(ℓ) → Cl2(g) + H2(g) + 2NaOH(aq)

 

78 Explain, in terms of energy, why this cell is an electrolytic cell. [1]

Answer-->Electrical energy is required to cause a reaction

79 Explain, in terms of ions, why the aqueous solution in the cell conducts an electric current. [1]

Answer-->The solution contains mobile ions.

80 State the oxidation number of oxygen in the aqueous product. [1]

Answer-->  -2

81 Compare the pH value of the solution before the battery is connected to the pH value of the solution after the cell operates for 20 minutes. [1]

Answer-->pH increases

 

Next-->Questions 82-85

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Questions 51-52 Questions 53-54 Questions 55-58 Questions 59-60 Questions 61-65 Questions 66-68 Questions 69-72 Questions 73-77  Questions 78-81  Questions 82-85

 

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